Technical Field
The present invention relates to control of power supply of a plurality of machines which operate in association with each other. Particularly, the present invention relates to a device, a method, a program, and a recording medium, each of which is for controlling the power supply of the plurality of machines.
Related Art
Conventionally, there has been known manufacturing lines in which a plurality of machines (automated machines) successively carry out processing or assembly of electronic parts or mechanism parts. According to such manufacturing lines, all of the plurality of machines are simultaneously turned on. Then, a start timing of the processing or the assembly is controlled based on detection, by a sensor such as a photoelectric sensor and a limit switch, of an object to be subjected to the processing or the assembly. Therefore, the plurality of machines are always turned on and, consequently, consume standby electric power which does not contribute to manufacturing. Further, in a case where a heat treatment device, such as a molding machine, a reflow furnace, or a drier, is provided in the manufacturing line, the heat treatment device is controlled so that a temperature in furnace is kept high, for the purpose of reduction in time for increasing the temperature in the furnace to an appropriate temperature. This causes the heat treatment device to operate even in a case where no object to be subjected to the processing or the assembly exists in the furnace. It follows that the heat treatment device consumes electric power due to such idle operation.
FIG. 7 is a view illustrating changes per unit of time in amounts of electric power consumption in a manufacturing line in which machines A through D are arranged in this order. Note here that the machine A is a metal press, the machine B is an injection molding machine, the machine C is an inspection device, and the machine D is an exhaust fan. According to FIG. 7, during a time period “a”, the manufacturing line is in normal operation, and each of the machines A though D consumes some degree of electric power. In contrast, during time periods b through e, part of the machines A through D consumes no electric power or only a small amount of electric power, and processing of a product is not carried out.
For example, during the time period “b”, the machine A is stopped. Accordingly, a workpiece (an object to be processed) is not supplied from the machine A to the machines B though D. That is, the machines B through D cannot process the workpiece. It follows that electric power consumed by the machines B though D is wasteful standby electric power which is not concerned with manufacturing.
The time period “c” is a time period during which an operator switches with another operator at night. During the time period “c”, the machines A and D are turned off, while the machines B and C are turned on so as to be in a standby state. In a case where a standby time is short, the machine B, which is an injection molding machine, needs to perform warm-up operation because the machine B requires time to be restarted after being turned off. Meanwhile, the machine C, which is an inspection device, does not require time to be restarted. It follows that the machine C consumes wasteful standby electric power.
The time period “d” is a time period during which an operator switches to another operator in morning. During the time period “d” herein, it is forgotten to turn off the machine D, which is an exhaust fan. In this case, the machine D consumes wasteful electric power. The time period “e” is a time period during which the manufacturing line is not in operation (non-operation day). During the time period “e” herein, it is forgotten to turn off the machine C, which is an inspection device. In this case, the machine C consumes wasteful electric power.
Due to a recent growing recognition of importance of a reduction in carbon dioxide, reduction in standby electric power or wasteful electric power consumption caused by idle operation described above has been demanded.
It has been considered to control a standby time of each machine or idle operation performed by each machine by monitoring, in detail, a workpiece being transferred with the use of a plurality of sensors such as photoelectric sensors and limit switches. However, a state of a workpiece, the number of workpieces, a frequency of transfer of a workpiece vary depending on a machine. However, a most suitable sensor should be selected for each machine or a control condition should be set for each machine. Furthermore, an increase in number of sensors causes an increase in facility cost.
Patent Literature 1 discloses a technique of controlling power supply of each machine to be turned on/off with the use of a controller with reference to schedule information indicative of an operation schedule time table of the each machine. With this, the each machine is caused to be in standby state or perform idle operation in accordance with the operation schedule time table, thereby reducing electric power consumption. However, with high frequency, progress in a manufacturing line changes, so that the progress is behind or ahead the schedule. In this event, even though it is necessary to operate the each machine regardless of the schedule, the power supply of the each machine is automatically turned off in accordance of the schedule. Therefore, it is difficult to employ this technique from a practical aspect.
According to the method for controlling a manufacturing line disclosed in Patent Literature 2, a monitoring section which monitors an amount of electric energy is provided to at least one of machines provided in a manufacturing line. By controlling a power supply control section of another machine in accordance with the amount of electric energy monitored by the monitoring section, wasteful electric power consumption is suppressed.